Superflexpy

Change log

Minor changes
- [Pull request](https://github.com/dalmo1991/superflexPy/pull/9) from [alessandro-mariotti-zupit](https://github.com/alessandro-mariotti-zupit) that upgrades python and packages versions.

Change log

Minor changes

- Added the classifier `Topic :: Scientific/Engineering :: Hydrology`

Change log

Major changes to existing components

- `ODEsElements` can now return the derivative of the fluxes together with the fluxes. This enables the usage of numerical solvers that use the derivatives (e.g., Newton methods).
- Folder structure improved. The numerical approximators and the root finders have been moved from the folder `implementation/computation` to `implementation/numerical_approximators` and `implementation/root_finders`, respectively. Names of the files have been slightly modified to be coherent with this new folder organization.

New code
- Implemented a new numerical approximator implementing Runge Kutta 4
- Implemented a new root finder implementing a Newton-bisection method
- Implemented a new root finder implementing a trivial algorithm to solve explicit algebraic equations.

In the `Network` class, changed argument `topography` to `topology`

- The abbreviation of "differential equation" changes, in the code, from
:code:`dif_eq` to :code:`diff_eq`. This change regards variables names, both
in the methods arguments and implementation.

- The class :code:`FastReservoir` has been changed to :code:`PowerReservoir`. No
changes in the functionality of the class.

- Testing improved.

- BugFix
- Change of license